This invention relates to a paper feeding device for a box making machine which supplies flat, cut paper of a predetermined shape during predetermined intervals for bending and pasting.
Heretofore, a paper feeding device 10 shown in FIG. 3 was used. The paper feeding device 10 is constructed such that laminated paper 12 is stacked and mounted on a paper feeding belt conveyor 11 and the paper is fed one sheet at a time through a gap at the lower end of a shutter 13. The shutter 13 abuts the front end of the paper 12. A timing correcting conveyor 16 is used to feed the paper through a drawing belt conveyor 14. The paper is then pushed by a pawl 15 mounted on a chain. Thus, the paper is supplied at predetermined intervals. In the device 10, the paper from the drawing belt conveyor 14 may ride up onto a pawl 15 of the timing correcting conveyor 16, and is thus not properly fed downstream. In order to prevent this from occuring, the laminated paper 12 on the feeding conveyor 11 is stopped from being fed using a bar 17 provided between the belts. The bar 17 lifts the stack at predetermined intervals and thus, the paper is fed intermittently from a paper feeding belt conveyor 11.
In the device 10, when the stack of laminated paper 12 is lowered by bar 17 and the paper starts to feed onto the paper feeding belt conveyor 11, slippage can occur temporarily between the paper and the belts. The slipping time is variable among the paper sheets so that the paper feeding belt conveyor 11 does not accurately feed the paper in sychronization with the timing correcting conveyor 16 so that an operation defect such as the paper riding up onto the pawl 15 tends to occur. Also, the tendency for this operation defect to occur is increased at higher operational speeds, and thus it is difficult to speed up the operation of the device 10. Furthermore, when the paper 12 stacked on the paper feeding belt conveyor 11 moves vertically, the ratio of the time of lifting the paper to the time of lowering the paper must be adjusted according to a) the entire length of the paper and b) the speed of the paper feeding onto belt conveyor 11. However, this adjustment requires much trial and error and also numerous cumbersome operations are also required.